Red Bull says Verstappen's Canadian GP defence shows Renault gains

Verstappen defended fourth place from Rosberg over the course of several laps in the closing stages of the race, with the Mercedes driver sliding into the runoff area at the final chicane after an attempted pass.

At the Montreal race last year, as Renault struggled for power and reliability, both Red Bulls finished a lap down.

But Renault has made gains this season with Red Bull winning in Spain and only missing out on victory in Monaco due to a pitstop mix-up.

"In previous years he [Rosberg] would have gone past no matter which side he picked," said Horner, referencing Verstappen's ability to hold Rosberg off on the long back straight in Montreal.

"So for Max to be able to defend the way he did - he wouldn't have been able to do that 12 months ago."

Horner described Renault's progress, which involved an update introduced in Monaco, as a "step in the right direction".

"We've still got more to go, but for this circuit that is power dominated, compared to 12 months ago where we were a lap behind... we were 1.5s off in qualifying last year, this year we're three tenths away," he said.

"So it really is a step in the right direction.

"There will be some tracks where Ferrari will be stronger, and hopefully we'll have our days where we are stronger as well."

Red Bull and Renault had a frosty relationship last year, which resulted in the team terminating its contract with the French manufacturer before both parties agreed to continue together after all.

Horner believes the relationship is now in a stronger place and he is hopeful that will continue to yield better results.

"It's in very good shape," he said. "Yes, there was tension and a lot of debate, and frustration, last year.

"It was a catalyst for change.

"The positive outcome has been the restructuring that has gone on there, the personnel that have been brought in.

"[Engine technical director] Remi Taffin and the team he has assembled around him - you can see the progress is very clear.

"The trajectory that Renault are on now is very encouraging for the future."